Electromagnetic device



Aug. 2'9, 1933.

H. C. GRAVES, JR., ET AL ELECTROMAGNET I C DEVICE .Filed OCT,

4 Sheets-Sheet l A TTORNE Y Aug 29, 1933- H. c. GRAVES, JR., ETA.1,924,686

ELECTROMAGNETIC DEVICE 11, lso

4 Sheets-Sheet 2 Filed Oct.

ATTORNEY H. c. GRAVES, JR., ET AL 1,924,686

Aug. 29, 1933.

ELECTROMAGNETIC DEVICE Filed Oct. 11, 1930 4 Sheets-Sheet 3 IVNR gm;ATTORNEY Aug. 29, 1933. H. c. GRAVES, JR.'v ET AL 1,924,685

ELECTROMAGNETIC DEVICE Filed dot. 11, 1930 4 Sheets-Sheet 4 INVENToRsM.; )A

ATTORNEY.

Patented Aug. 29, 1933 UNITED STATES PATENT OFFICE Chester County,

and Henry J. Schmid,

Philadelphia, Pa., assignors to I-T-E Circuit Breaker Company,Philadelphia, Pa., a corporation of New Jersey Application October 1l,1930. Serial No. 487,978

39 Claims.

Our invention relates to electromagnetic devices, and particularly totripping apparatus associated with automatic circuit breaker mechanismadapted specifically to control the circuits of electric motors. v

In accordance with our invention, the time interval after whichactuation of the tripping mechanism is eifected under high currentconditions, as during starting of a motor, is increased with little orno effect upon the time interval alter which the trip is actuated underlower current conditions, by providing in shunt to the movable armatureof retarded action tripping mechanism a magnetic leakage path which isof relatively low reluctance at high current values and of relativelyhigh reluctance at comparatively low current values.

More particularly, the shunt path includes a second movable armaturewhich in addition to increasing the holding time of the first armatureis eiiective instantaneously to actuate the tripping mechanism uponoccurrence of excessively high current conditions.

Preferably both armatures are adjustable, and more particularly are sorelated that they are simultaneously adjustable, the reluctance or" theretarded action armature circuit or path changing more rapidly than thereluctance of the instantaneous trip armature circuit.

More specifically, our invention relates to improvements in that 'formof tripping mechanism embodying a single tripping coil employed toactuate two separate armatures, or equivalent, under respectivelydifferent circuit conditions, as

` exemplified in copending Scott application, Serial No. 354.480, ledApril 12, 1929, patented June 20, 1933, No. 1,914,582.

Our invention further resides in the features of construction andarrangement hereinafter described and claimed.

For an understanding of our invention, and for illustration of some ofthe various forms it may take, reference is to be had to theaccompanying drawings, in which:

Fig-.41S a detail View disclosing modified armature structure.

Fig. is a side elevational view of another modification.

(Cl. G- 109) Fig. 6 is a side elevational view of a further modication.

Referring to Fig. 1, the laminated core 1, suitably secured to andextending perpendicularly from the panel l?, is provided with the polepieces G0 2 and 3, the latter having the auxiliary pole extensions 4extending therefrom, the lower faces of the pole pieces and poleextensions lying substantially in the same horizontal plane. The coil 6FL) 21 encircles the core 1, and is ordinarily traversed by currentflowing in the circuit to be controlled as hereinafter described.

The supports 20, 20, secured on opposite sides of the rear pole piece 2,project downwardly therefrom. The pin 6, extending between the supports,just below the pole piece 2, carries a laminated armature 5, which is ofsuch length as substantially to cover the outer pole piece when in itsupper position, the upper surface of the armature then lying in theplane of the magnet pole faces.

The weight of the armature is normally supported by a link 10 fittedinto a recess in the bottom of the armature and hinged thereto by a pin9, the link passing through an opening in the top 11 of the casing 12,and at its lower end being hinged to the adhesive plate or sucker disc14 by the pin 13. The disc 14, and the bottom of the housing 12, withoil within casing 12 comprise a start-delaying device well known in theart, for the armature 5. Briefly, for currents through coil 21 in excessof a predetermined value, the armature 5 will be released after a timeinterval whose duration is inversely related to the current, that is thetime interval becomes shorter as the current increases.

The yoke 7 of non-magnetic material, as brass, embraces the movablearmature 5 and is pivotally mounted upon the pin 8 extending between thesupports-20 substantially more remote from the pole piece 2 than the pin6 which carries the armature 5 so that the air gap between pole piece 2and armature 1S is relatively large compared to the air gap between polepiece 2 and armature 5. An armature 18 is secured to the inside of eachleg of the yoke in such position that when the yoke is in its upperposition the armatures 18 lie in the plane of the magnetic pole faces.The armature 5 and the armature system comprising the yoke 'l andarmatures 18 move between their upper and lower positions Withoutmechanical interference with the other.

The outer end of the armature 5, as it approaches the pole piece S,strikes the end 24 of the tripping member 25, which'is slidably held ina groove by the support 16. The plate 26, shown more clearly in Fig. 3,which is mounted upon the pin 27 extending outwardly from the trippingmember 25, is adapted to be engaged by the yoke 7 as it approaches orreaches the upper limit of its travel. The plate 26 floats or is freelypivoted on pin 27 and is normally held in a substantially horizontalposition by the shoulder 16a of the support 16. If for any reason, asslight inaccuracy of manufacture or Wear, the plate 26 is engaged by onearm of yoke 7 before the other, it rocks upon pin 27 until both armsengage it, whereupon further movement of the yoke is transmitted to thereciprocal member 25, avoiding any binding of the latter in litsguideway.

The construction and operation of the apparatus actuated by the trippingmember 25 form, per se, no part of the present invention, though oneform is described and illustrated to make clear the operation andadvantages of our invention. When the tripping member 25 moves upwardly,it engages the under side of the setting lever 28, causing it to rotateabout the pivot 29 and breaking the toggle formed by lever 28 and thelink member 30 pivoted thereto at 31. Upon collapse of the toggle, thecontact supporting member 32, connected to the other end of link 30,rotates in clockwise direction, as viewed inl Fig. 1, to move thecontact member 83 out of engagement with the stationary contacts 34, 34supported by the panel 17, breaking the circuit which includes the coil21.

For large circuit breakers, it may be necessary or desirable tointerpose between the tripping member 25 and the locking mechanism ofthe breaker, a suitable mechanical relay in order that the forceutilized may be sufficiently great positively to eect opening of thebreaker.

The armature 5 and the yoke 7 with its attached armatures 18 are bothnormally held down by gravity, the former being supported by the link10, as above described, and the yoke 7 resting on a projection or stop15 secured to or integral with the casing 12. This projection may befiled for calibration adjustment. A vertical adjustment of the positionof the housing 12, which is notched or grooved partially vto surroundthe support 16 to prevent rotation as it is moved -along the support bythe knob 22, which normally clamps it thereto, simultaneously adjuststhe armature 5 and yoke 7 As the distance between the pivot 6 of thearmature 5 and its link pin 9 is much less than the distance between thepivot 8 of the yoke 7 and its point of engagement with the lug 15, therelative positions of the armature 5 and the yoke 7 change as the casingis moved or adjusted in a vertical direction, the air gap betweenarmature 5 and the pole piece 3 changing more than the air gap betweenthe pole piece 3 and the armatures 18 for any given increment ofadjustment of casing 12.

When current ows through the coil 21, a. magneto motive force existsbetween the poles 2 and 3 which produces a ux between the polestraveling in several paths. There is direct leakage flux from pole 2 topole'3 through the air; a leak age path from the pole 2 into Ythearmature 5 and thence to pole piece 3; a leakage path from the polepiece 2 into armature 5, thence to armatures 18 and therefrom to thepole piece 3 and extensions 4; and the side leakage path from the sidesof the pole piece 3 directly to the armatures 18. The distribution ofthe total flux depends upon the relative positions and masses of thearmatures and the flux densities. 'Ihe armatures 5 and 18 form parallelmagnetic paths between the pole pieces 2 and 3. Since the permeabilityof the several air gaps is constant, while the permeability of the ironof the armatures is constantly decreasing as the flux density increases,the relative ilux values in the several paths above mentioned willchange as the current changes. For example, with increased current flowthe relative value of the lux from the pole piece 2 into the armature 5and thence into pole piece 3 will decrease and the flux through theshunt paths relatively increase. The armatures 18, therefore, exert ashading or diverting eiect on the armature 5 which is insubstantial orslight for low current values and of increasing effect at high currentvalues. The armatures 18 for all positions of yoke 7 are substantiallyspaced from the pole piece 2 to insure that the major part'of the fluxtraveling from the pole piece 2, which reaches the armatures 18, firstpasses through armature 5. Most of the flux which enters armatures 18from armature 5 enters across an air gap which is substantially ofuniform length and approximately constant area. As a result the magneticpull on the armatures is substantially independent of their relativepositions under pole piece 2, and largely dependent upon their relativepositions to pole piece 3 and pole piece extension 4.

By constructing the armature 5 so that it will be saturated under heavycurrent conditions, a definite ratio between the current values ofinstantaneous tripping and the setting of armature 5 may be obtained.Alternatively, it is possible to obtain a constant instantaneoustripping point for all positions of the retarded armature or to obtainany desired relation by suitable design and position of the armatures.

The circuit breaker described utilizing this tripping mechanism isparticularly adapted for use in motor starting systems in which, forexample', the motor is connected directly across the line without theintroduction of starting resistances, or the like. Initially, uponclosing of the motor circuit by moving lever 28 to the position in Fig.1, there is a rush of current through the coil 1 which is many times thenormal or running current. In the absence of armatures 18, orequivalent, and particularly if the motors are starting under load, thearmature 5 may be attracted, tripping the circuit breaker andinterruping the desired starting operation. If the armature 5 isadjusted to a higher tripping point, as by changing the position of thecasing 12, to prevent this unnecessary tripping during starting, thereis danger that under running conditions the breaker will not open exceptafter a prolonged interval of overload, damaging the motor andcircuit-breaker windings.

When the current values are normal, as under running conditions, theflux density'in armature 5 does not approach the saturation point, andthe reluctance of the armature will be relatively low with respect tothe reluctance of the path through armatures 18 which have longer airgaps and usually less cross-sectional area than armature 5, so that asmall amount only of the total flux produced by the current in the coil21 ows through armatures 18 under normal conditions. When the currentincreases to very high or abnormal values, however, this causes anincreasingly high ux density in armature 5, and the reluctance ofarmature 5 increases as the ilux density increases, so that anincreasing percentage of the total flux will now through armatures 18.When the armatures 18 are utilized as above described, they afford,under starting conditions, a path in shunt to the armature 5 which is ofrelatively low reluctance since its flux density is low at this time,With the eiect that the pull exerted by the magnet on armature 5 isdecreased by the presence of armatures 18, and therefore the timeinterval in which the tripping system comprising the armature 5 and thetime-delay device 14 may act is considerably increased which permits themotor to start, even when under load, Without tripping of the breaker.As the motor comes up to speed, the current drops due to the relativelyhigher counter electro-motiveforce, and the current through the coildrops to the normal running value. Under normal running conditions theforce exerted upon the armatures 5 and 18 is not suflicient to attract.For a range of current values corresponding to ordinary overloads, thearmature 5 affords a path of low reluctance compared to the path formedby armature 18, so that the normal operation of the tripping systemcomprising the armature 5 and the retarding device connected thereto isnotv substantially'aiected by the presence of the armatures 18. Uponoccurrence of excessively high current through the coil 21, asoccasioned,

for example, by short circuits, the armatures 18 are instantaneouslyattracted to trip the circuit breaker, independently of armature 5.

If the instantaneous trip is not required, and only the increasedholding time during-starting is desired, stationary iron vanes may bedisposed adjacent armature 5 to promote high ux leakage, in substitutionfor the armatures 18. By adjusting these vanes toward or away from poles2 and 3, the time-delay of armature 5 may be increased or decreased atwill. The retarded action feature may be dispensed with, if desired, bydisconnecting armature 5 from the suckerdisk, or by omitting the latterand its appurtenances. The current value at which the armature 5 isattracted may be predetermined by adjusting magnetizable structureforming a magnetic path in shunt thereto, for example armatures 18, ornormally stationary but adjustable vanes.

While it is convenient, it is not necessary to pivot the yoke 7 and thearmature 5 at diierent points. For example, as in Fig. 4 both the yoke 7and armature 5 may be supported by the Asingle pin 6. However, the yoke7 does not extend parallel toarmature 5, but lis provided with an offsetportion 36 adjacent the pivot pin 6` of such length that the remainderof the yoke yand the armatures 18 bear substantially the same relationto armature 5 and pole pieces 2 and 3, as in Fig. 1, when the modiedyoke 7' is in its lower position, f

A further modication of our invention is disclosed in Fig. 5. Thearmature 18 is pivotally mounted on pin 8', the position of the armaturewith respect to the additional pole 37 having the pole face 4' beingdetermined by the stop 38, which, as indicated, may be adjustable. Theeld structure 37 and armature 18 form a leakage path in shunt toarmature 5, as in the prior modications, which is so designed that itsreluctance for high current values corresponding in range to thestarting currents, is low compared to the reluctance of the pathincluding the armature 5, with the result that there is afforded anincreased time for starting. For currents in excess of normal runningcurrents the armature 5 and the associated retarding mechanism, Whichmay be identical to that previously described, provides normal delayedtripping protection, the armature 5 engaging the tripping member 25 toraise lever 28 which eiects counterclockwise movement vof lever 28 torelease circuit breaker mechanism, interrupting the circuit includingthe coil 21 and apparatus sought to be protected. When the currentvalues are excessively high, the armature 18 instantly effects trippingby engaging the projection 39 of member 25 effecting its movement totrip or release the circuit breaker, or equivalent.

It will be understood that the construction may differ from the examplesshown or described, without departure from our invention. For example,the armatures 5 and 18, or equivalents, may be of the plunger type forcooperation with a solenoid, which is comprehended by the term coil asused in the claims. More specically, the plungers may be concentric. Forexample, referring to Fig. 6, the plunger armature 5a adapted toreciprocate axially of the solenoid 21a is connected to the suction disk14 of the startdelaying device 12. Preferably, the skirt member 37threaded or otherwise suitably connected to the lower end of thearmature 5a is provided to cooperate with the plate 11 to guide thearmature 5a when moving in response to the attraction of solenoid 21a.The interior of this armature which is hollow is preferably providedwith a lining 38 of non-magnetic material to prevent sticking thereto ofthe second plunger armature 18a which nests within armature 5a andnormally rests upon the bottom of lining 38. The purpose and operationof the two armatures correspond to that of the armatures 5 and 18 of thepreceding modications and is not repeated in full.

Briefly, for current values that are excessively high, the armature 18ais moved independently of armature 5a, moving the tripping member 25a,which may, as indicated, project therefrom through the pole piece 3awith which it cooperates to guide the armature, into engagement with theprojecting part 28h of the switch arm 28a, breaking the toggle holdingthe movable switch contacts 33 in engagement with the fixed contacts 34.For currants less than those necessary to operate armature 18a, but inexcess of normal values, the armature 5a and the start-delaying device12 provide normal delay tripping operation, the armature 5, upon upwardmovement, carrying with it the armature 18a which through trippingmember 25a, opens the switch or circuit breaker. During starting, therelative reluctances of the paths formed by the armatures between thepoles 2a and 3a, are such that the time-current characteristic ofarmature 5a and start-delaying device 12 is modified, to avoid trippingby the momentary surge of current when the circuit breaker or switch isrst closed, as in the starting of a motor.

As in the preceding modifications, both armatures are simultaneouslyadjustable by the knob 22, or equivalent, which clamps the iixed or potmember of the start-delaying device 12, against the frame 16a..

While the magnetic device has been specically illustrated and describedas a tripping device for a circuit breaker which must be reset, it maybe utilized as a relay by mounting a contact member for direct actuationby the member 25, for example, so that a circuit will be made or brokenwhen armature structure is actuated by the coil 2l, or equivalent, andbroken or made when the coil is de-energized.

What We claim is:

l. An electromagnetic tripping device comprising a coil, a trippingsystem comprising a movable armature and time-delay structure associatedtherewith responsive to passage through said coil of current ofmagnitudes lying within a predetermined range, and means for increasingthe lag of said tripping system when the magnitude of said current liesin the upper portion of said range comprising magnetizable structureforming a path in shunt to said armature when said current is of saidlast-named magnitude.

2. An electromagnetic tripping device comprising a coil, a trippingsystem comprising a movable armature and time-delay structure associatedtherewith responsive to passage through said coil of current ofmagnitudes lying within a predetermined range, and a second armaturenormally stationary in predetermined position to provide a path in shuntto said movable armature, of relatively low reluctance when themagnitude of said current lies in the portion of said range to increasethe time delay of said system and movable instantaneously to eiecttripping when the current through said coil is of a magnitudesubstantially in excess of the greatest magnitude of the rangeaforesaid.

3. An electromagnetic device comprising a coil, stationary corestructure therefor having pole pieces, an armature movable substantiallyto complete the magnetic path between said pole pieces, a retardingdevice connected to said .movable armature, and masses of magneticmaterial on both sides of the path of movement of said armatureproviding between said pole pieces a magnetic path of relatively lowreluctance for high values of current traversing said coil to decreasethe pull exerted upon said movable armature thereby to increase thetime-delay afforded by said retarding device.

4. An electromagnetic device comprising a coil, stationary corestructure therefor having pole pieces, an armature movable substantiallyto complete the magnetic path between said pole pieces, a retardingdevice connected to said movable armature, and a second movable armatureforming a magnetic path in shunt to said rst armature so disposed thatfor all positions thereof a substantial air gap exists between saidsecond armature and one of said pole pieces..

5. An electromagnetic tripping device comprising a coil, stationary corestructure therefor having pole pieces, an armature pivoted adjacent oneof said pole pieces and movable substantially to complete the magneticpath between them, a retarding device connected to said armature, and asecond movable armature plvoted more remotely from said one of said polepieces for effecting instantaneous tripping for excessively highcurrents.

6.\ An electromagnetic device comprising a coil, stationary corestructure therefor having pole pieces, an armature pivoted adjacent oneof said pole' pieces and movable substantially to complete the magneticpath between them, a retarding device connected to said armature, asecond movable armature pivoted -more remotely from said one of saidpole pieces, and means for varying the position of the ,armatures withrespect to each other and to said pole pieces.

'7. An electromagnetic tripping device for a circuit breaker adapted tocontrol a motor circuit comprising a coil traversed by the motorcurrent, a tripping system comprising a movable armature and time-delaystructure associated therewith effecting opening of said breaker uponoccurrence of overload during running of said motor, and means formodifying the characteristic of said system during starting of saidmotor comprising magnetizable structure affording a path in shunt tosaid armature of relatively low reluctance under high current conditionsof starting.

8. An electromagnetic tripping device for a circuit breaker adapted tocontrol a motor circuit comprising a coil traversed by the motorcurrent, a tripping system comprising a movable armature and time-delaystructure associated therewith effecting opening of said breaker uponoccurrence of overload during running of said motor, and a secondarmature unattracted lor current values no greater than those ofstarting for providing a magnetic path in shunt to said armature of lowreluctance under high current conditions of starting to avoidunnecessary tripping of said breaker and of relatively high reluctancefor materially less current values to permit normal operation of saidsystem under running conditions, and attracted instantaneously to tripsaid breaker upon existence at any time of current values in excess ofstarting values.

9. An electromagnetic tripping device for a circuit-breaker comprising acurrent coil, a tripping system comprising a movable armature and aretarding device connected thereto affording an inverse time-currentcharacteristic throughout a range oi current values, and means forretarding the action of said system for current values above said rangecomprising magnetizable structure providing in shunt to said armature apath of relatively low reluctance for current values above said rangeand of relatively high reluctance throughout said range.

10. An electromagnetictripping device for a circuit breaker comprising acurrent coil, a tripping system comprising a movable armature and aretarding device connected thereto affording an inverse time-currentcharacteristic throughout a range of current values, and a secondarmature, unattracted throughout said range and a higher range ofcurrent values, for providing a path of relatively low reluctance inshunt to said first armature for said higher range to increase theinterval before tripping throughout said higher range with insubstantialeffect throughout said lower range, and attracted for current values inexcess of the higher range to effect substantially instantaneoustripping of said circuit-breaker independently of said first armature.

11. An electromagnetic device comprising a coil, core structure thereforhaving pole pieces, an armature movable substantially to complete themagnetic path between said pole pieces,y a start-retarding deviceconnected to said armature, and magnetizable structure on either side ofsaid armature affording magnetic paths in shunt to said armature withrelatively large air gaps between said structures and one of said polepieces.

12. An electromagnetic device comprising a coil, core structure thereforhaving pole pieces, a pivoted armature movable substantially to completethe magnetic path between said pole pieces, a start-retarding deviceconnectedto said armature, and a pivoted support carrying magnetizablestructure on either side of said armature affording magnetic paths inshunt to said armature with relatively large air gaps between saidstructures and the pole piece adjacent the pivoted end of said support.

13. An electromagnetic tripping device for a circuit-breaker comprisinga coil, core structure therefor having pole pieces, an armature pivotedadjacent one of said pole pieces, a pivoted yoke embracing said armaturecarrying a magnetizable member on each side of said armature affordingmagnetic paths in shunt thereto with large air gaps between said membersand the pole piece adjacent the pivoted ends of said armature and yoke,and means for varying the air gap between said members and the other ofsaid pole pieces,

and to greater extent the air gap between said armature and said otherpole piece while insubstantially varying said large air gaps.

14. An electromagnetic device comprising a coil, stationary corestructure therefor having pole pieces, a movable armature pivotedadjacent one of said pole pieces, a start-retarding device connected tosaid armature, and magnetizable structure forming a magnetic path inshunt to said armature so disposed that the reluctance of the air gapbetween said structure and the pole piece adjacent the pivoted end ofsaid armature is greater than the reluctance of the air gap between saidstructure and said movable armature.

15. An electromagnetic device .comprising a coil, stationary corestructure therefor having pole pieces, a movable armature pivotedadjacent one of said pole pieces, means to adjust the free end of saidarmature toward and away from the other pole piece, a start-retardingdevice connected to said armature, and magnetizable structure forming amagnetic path in shunt to said armature so disposed that for allpositions of said armature the reluctance of the airl gap between saidstructure and said armature is substantially constant and less than thereluctance of the air gap between said structure and the pole pieceadjacent the pivoted end of said armature.

16. An electromagnetic tripping device comprising a coil, stationarycore structure therefore having pole pieces, an armature pivotedadjacent one of said pole pieces and movable substantially to completethe magnetic path between them, a retarding device connected to saidarmature, and a second movable armature pivoted more remotely from saidone of said pole pieces for providing in shunt to said first armature amagnetic path of relatively low reluctance for high values of currentthrough said coil and for effecting instantaneous tripping forexcessively high currents.

17. An` electromagnetic device comprising a coil, stationary corestructure therefor having pole pieces, an armature pivoted adjacent oneor" said pole pieces and movable substantially to complete the magneticpath between them, a retarding device connected to said armature, asecond movable armature pivoted more remotely from said one of said polepieces for providing in shunt to said rst armature a magnetic path ofrelatively low reluctance for high values of current through said coil,and means for varying the position of the armatures with respect to eachother and to said pole pieces.

18. An electromagnetic device comprising a coil, a system comprising anarmature and timedelay structure associated therewith, and means forincreasing or decreasing the retarded action of said system comprisingadjustable magnetic structure forming a magnetic path in shunt to saidarmature.

19. An electromagnetic device comprising a coil, a system comprising anarmature and timedelay structure associated therewith, magnetizablestructure forming a path in shunt to said armature, and means foradjusting said armature and said magnetizable structure to effect apredetermined time-current characteristic of said system.

20. An electromagnetic circuit controlling device comprising a coil, acontact system, an armature and time delay mechanism associatedtherewith responsive to passage through said coil of current ofmagnitudes lying within a predetermined range for actuating said contactsystem, and a second armature adjustable relative to said iirst armatureto effect a predetermined timecurrent characteristic of the controllingdevice and movable instantaneously to effect actuation of said contactsystem upon passages through said coil of current of a magnitudesubstantially in excess of the greatest magnitude of the rangeaforesaid.

21. An electromagnetic device comprising a coil, a pivoted armature, atime-delay device connected thereto, a second pivoted armature, and areciprocable element selectively actuatable by said armatures.

22. An electromagnetic circuit-controlling device comprising a coil, apivoted armature, a timedelay device connected thereto, a second pivotedarmature, and a reciprocable contact-actuating member selectivelyactuatable by said armatures.

23. An electromagnetic device comprising a coil, pivoted armaturestructure comprising a yoke, a reciprocable member, and a pivotedelement disposed in the path of movement of the arms of said yoke fortransmitting movement thereof to said reciprocable member.

24. An electromagnetic device comprising a coil, telescoping plungerarmatures therefor, one of said armatures adapted for instantaneousmovement, and the other armature having startdelaying means associatedtherewith.

25. An electromagnetic device comprising a coil, a hollow plungerarmature in the field thereof, a second plunger armature normally withinsaid rst armature adapted for instantaneous movement, and start-delayingmeans associated with said iirst armature.

26. An electromagnetic tripping device comprising a coil, a hollowplunger armature in the iield thereof, a second plunger armaturxnormally within said rst armature and supported thereby, start-delayingmeans associated with said first armature, and holding mechanism trippeddirectly by the second armature under certain current conditions andthrough the second armature by said first armature under other currentconditions.

lll5

27. An electromagnetic tripping device comprising a solenoid, a pair ofconcentric plungers reciprocable axially of said solenoid,lstart-delaying mechanism connected to only one of said plungers, andtripping structure actuable upon movement of either of said plungers.

28. An electromagnetic circuit controlling device comprising a contactsystem, a coil, and a multiplicity of armatures reciprocable axially oisaid coil to operate said contact system, each of said armatures adaptedto be actuated by said coil upon occurrence of respectively diiferentcurrent conditions, and at least one of said armatures being associatedwith a time-delay device.

29. An electromagnetic tripping device for a circuit breaker comprisinga coil, pivoted armature structure comprising a yoke, a tripping member,a guideway therefor, and a plate pivotally.

connected to, and extending from said member on both sides thereof inthe path of movement of the arms of said yoke for transmitting movementof said yoke to said tripping member.

30. An electromagnetic device comprising a coil, a pivoted armature, amember in the path of movement of said armature, pivoted armaturestructure comprising a yoke embracing said rst armature, and an elementpivotally connected to and extending from said member on both sidesthereof i n the path of movement of the arms of said yoke.

31. Electromagnetic tripping mechanism including a coil, an armaturemovable in the field of said coil in response to passage therethrough ofcurrent of magnitudes lying Within a predetermined range, meansassociated with said armature for delaying its action, and further meansfor substantially delaying the time at which said armature acts when themagnitude of said current lies in the upper portion of said rangecomprising means for diverting from said armature part of the totalmagnetic flux produced by said coil when said current is of saidlast-named magnitude.

32. Electromagnetic tripping mechanism including a coil, an armaturemovable in the field of said coil in response to passage therethrough ofcurrent of magnitudes lying within a predetermined range, meansassociated with said armature for delaying its action, and further meansfor substantially delaying the time at which said armature acts when themagnitude of said current lies in the upper portion of said rangecomprising means for diverting from said armature part of the totalmagnetic ilux produced by said coil when said current is of saidlast-named magnitude, said last-named means comprising a second armaturecontrolling tripping in response to current through said coil when of amagnitude substantially in excess of the greatest magnitude of Vtherange aforesaid.

33.l Electromagnetic tripping mechanism in cluding a coil, an armaturemovable in the field of said coil in response to passage of currenttherethrough, means associated with said armature for delaying itsaction, and further means for substantially delaying the time at whichsaid armature acts comprising means for diverting from said armaturepart of the total magnetic ux produced by said coil.

34. Electromagnetic tripping mechanism including a coil, an armaturemovable in the field of said coil in response to passage of current ltherethrough, means associated with said armature for delaying itsaction, and further means for substantially delaying the time at whichsaid armature acts comprising means for diverting from said armaturepart of the total magnetic ilux produced by said coil, said last-namedmeans comprising a second armature controlling tripping upon attainmentof magnitude of current in said coil substantially in excess of themagnitude of current which normally sufiices to cause action of saidfirst-named armature.

35. An electromagnetic device comprising a coil, an armature, atime-delay device connected thereto, a second pivoted armature, and areciprocable contact-controlling member selectively actuable by saidarmatures.

36. Electromagnetic tripping mechanism including a coil, an armaturemovable in the eld of said coil in response to passage therethrough ofcurrent of magnitudes lying within a prede termined range, meansassociated with said armature for delaying its action, further means forsubstantially delaying the time at which said armature acts when themagnitude of said current lies in the upper portion of said rangecomprising means for diverting from said armature part of the totalmagnetic ilux produced by said coil when said current is of saidlast-named magnitude, and means for adjusting said fluxdiverting meansto vary the delay effect of saidr` second time-delay means.

37. Electromagnetic tripping mechanism including a coil, an armaturemovable in the field. of said coil in response to passage therethroughof current of magnitudes lying within a predetermined range, meansassociated with said armature for delaying its action, further means forsubstantially delaying the time at which said armature acts when themagnitude of said current lies in the upper portion of said rangecomprising means for diverting from said armature part of the totalmagnetic flux produced by said coil when said current is of saidlast-named magnitude, said last-named means comprising a second armaturecontrolling tripping in response to current through said coil when of amagnitude substantially in excess of the greatest magnitude of the rangeaforesaid, and means for adjusting the second armature to vary itsldelay effect upon said rst armature for said higher current values ofsaid range.

38. Electromagnetic tripping mechanism including a coil, an armaturemovable in the field to vary the'delay`r effect of the second armature.125

upon said first armature.

39. Electromagnetic tripping mechanism infcluding a coil, an armaturemovable in the fieldV` of said coil in response to passage of current'-therethrough, means associated with said armature for delaying itsaction, further means for substantially delaying the time at which saidarmature acts comprising means for diverting from said armature part ofthe total magnetic flux produced by said coil, said last-named meanscomprising a second armature controlling tripping upon attainment ofmagnitude of current in said coil substantially in excess of themagnitude of current which normally suices to cause action of saidrst-named armature, and means for adjusting the relative positions ofsaid armatures to vary the delay eiect of the second armature upon thefirst armature and the value of current required to actuate said secondarmature.

HERBERT C. GRAVES, JR. HENRY J. SCHMID.

CERTIETCATE 0F CORRECTION.

Patent No. 1,924,686. August 29, 1933.

HERBERT c. GRAVES, JR., ET AL.,

it is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 3.line 123, for "cui-rants" read currents; page 4, line 24, claim 2,before "portion" insert the word upper; and page 5. line 97, claim 20,for "passages" read passage; and that the said Letters Patent should beread with these corrections therein that the same may conform to therecord of the case in the Patent Office.

Signed and sealed this 21st day of November, A. D. 1933.

F. M. Hopkins (Seal) Acting Commissioner of Patents.

